Textile

ABSTRACT

A textile includes first and second conductive layers and at least one porous layer positioned between the conductive layers. The first and second conductive layers are arranged to generate an electric field whereby a current passes between the conductive layers inducing liquid transport and causing ions to be received at the second conductive layer. A measurement device is arranged to measure the amount of charge transferred between the first and second conductive layers during a liquid transport operation, the device taking account of any variation in current or voltage during the liquid transport operation. A control device is arranged to control a regenerating operation to regenerate the second electrode by transferring via it an amount of charge substantially equal to the measured amount so as to cause ions to be removed from the second conductive layer and thereby regenerate the conductive layer.

The present invention relates to a textile with increased watertransport ability.

It is well known that standard waterproof textiles typically transportonly 0.1 to 0.5 liters of water per square meter and hour, while humanperspiration rates are often 1-2 liters per hours during vigorousactivity. This creates challenges especially in foul weather clothingand in protective clothing such as fire-fighter or military uniforms,and can lead to reduced concentration and performance of wearers, inextreme cases hypo- or hyperthermia.

One solution is described in publications EP 0993328 and WO 2009/024779,where the liquid transport in aided by an electric field. By placing twoporous conductive layers on each side of a textile or porous membraneand applying a voltage difference between said layers, a water transportup to 100 liters per square meter and hour has been shown. The mechanismfor this transport is electroosmosis, which involves a small electriccurrent through the porous structure.

However, there are some important drawbacks with this solution. In orderto run a current between the electrodes, some electrochemicalcharge-transfer reaction must take place at the electrodes. For purewater this would involve the generation of hydrogen and oxygen, which isnot dangerous in small amounts, but could pose the danger of explosionsif in a non-ventilated system or if running high currents. With lowwater contents significant pH changes could appear near each electrode,potentially causing irritation to the skin. More serious challengesarise when contaminants are present, for example human sweat containingsodium chloride which could form dangerous chlorinated compounds uponelectrolysis at about 1.3 V. Due to kinetics, chlorine reacts at lowervoltages than oxygen in water. The creation of small gas bubbles couldalso dry out the pores and provide insulation at the electrodes,resulting in loss of performance.

Keeping the voltage below the reaction potentials of water and sodiumchloride (and other compounds present) could solve the problem. However,with standard electrodes no other reaction would be available to supportthe charge transfer, hence the water transport would stop and theelectrodes become polarized after a very short period.

The present invention addresses this, according to one aspect, byintroducing electrodes with an inherent charge transfer mechanism whichdoes not depend on the reaction potentials of the liquid to betransported, and for which the liquid is not taking part inelectrochemical reactions.

According to another aspect, the invention provides a textile comprisingfirst and second conductive layers, at least one porous layer positionedbetween the first and second conductive layers, the first and secondconductive layers being arranged to generate an electric field whereby acurrent passes between the conductive layers so as to induce liquidtransport and so as to cause ions to be received at the secondconductive layer, measurement means arranged to measure the amount ofcharge transferred between the first and second conductive layers duringa liquid transport operation, the measurement means being able to takeaccount of any variation in current or voltage during the liquidtransport operation, and control means arranged to control aregenerating operation to regenerate the second electrode bytransferring via it an amount of charge substantially equal to themeasured amount so as to cause ions to be removed from the secondconductive layer and thereby regenerate the conductive layer.

According to another aspect the invention provides a textile comprisingfirst and second conductive layers, at least one porous layer positionedbetween the first and second conductive layers, the first and secondconductive layers being arranged to generate an electric field, andmeans for reversing the electric field.

According to another aspect, the invention provides a textile pump withimproved electrodes to avoid un-desired electrochemistry.

In one embodiment, the electrode material is made from a hydrogenstoring material such as palladium or nanochrystalline nickel. Forpalladium, the oxidation and reduction of hydrogen occurs at only 0.3 V,hence an electric current causing electroosmotic liquid transport wouldhappen at only 0.3 V, far below the reaction potential for water orsodium chloride solutions. Such electrodes could thus safely transporteven salt containing water.

The following reactions take place at hydrogen storing conductive layers(electrodes):

-   -   1. Anode: H->H⁺+e⁻    -   2. Cathode: H⁺+e⁻->H

Thus, the hydrogen is stored in the electrodes as neutral atoms ormolecules, and moved through the porous liquid filled structure as ions.

An important aspect disclosed herein is the incorporation of a devicewhich counts the number of ions (charge) passing from one electrode tothe other. As these ions are the current carriers, this can be done byan automatic measuring of the current (i.e. the current is proportionalto the number of hydrogen ions transported). After applying the currentfor a certain period in one direction, the cathode would becomesaturated with hydrogen and the process would stop. Therefore, in apreferred embodiment of the present invention, an electronic controlsystem connected to the charge counting system would reverse the voltage(regeneration step) from time to time in order to avoid the saturationof one electrode or the emptying of the other.

It is known that membranes and textiles can have asymmetric watertransport properties, e.g. due to asymmetric pore structure along itscross section. The water transport could also be asymmetric e.g. due toliquid run-off at the outside of a jacket. Therefore, less water couldbe transported during the regeneration step, resulting in a net liquidtransport in the desired direction. Especially, in a jacket the forwardpumping could be applied during hard activity with high perspirationrates, and the regeneration could be carried out under dryer conditionsor when the jacket is not in use.

The pores of the porous layer may extend in a direction substantiallyperpendicular to the conductive layer.

Steps in operation of certain preferred embodiments of the presentinvention:

-   1. In a new system electrodes (conductive layers) are partially    pre-filled with hydrogen, to a known degree.-   2. A number of forward cycles (causing liquid transport in the    desired direction) and reverse cycles (causing electrode    re-generation) are carried out, while the total charge (equalling    the product of time and current) is counted and kept track of    electronically. This way, the degree of hydrogen filling in each    electrode is always kept track of. The length of the cycles can be    adjusted depending on the need for water transport. p0 3. The system    would automatically limit itself so as no electrode is saturated or    totally emptied of hydrogen (in which case the hydrogen cycling    would no longer work). The maximum time of operating the system in    one direction would depend on the current, which again depends on    voltage and liquid conductivity. For a given cycle it would also    depend on the degree of hydrogen saturation in the electrodes from    previous cycles.-   4. There could also be any number of periods with no voltage    applied, during which the hydrogen contents of each electrode would    remain constant. In other embodiments, ions different from hydrogen    would be the charge carriers, e.g. silver-silver chloride    electrodes. The charge counting and controlling system would be the    same, however.

A preferred embodiment is shown by way of example in the attacheddrawing, labelled as FIG. 1.

In the drawing:

1 is a porous textile or membrane where the liquid transport is to beinduced by an electric field and current, 2 is a conductive layer (firstelectrode), 3 is a conductive layer (second electrode), A is a pointwhere current is measured, and V is a voltage source. 4 is an electroniccontrol system connected to the current measurer A to reverse thevoltage (regeneration step) from time to time in order to avoid thesaturation of one electrode or the emptying of the other

Nanocrystalline nickel or other hydrogen storing metals could be usedfor the electrodes. Thin porous metal foils could be prepared by lasercutting a non porous foil, or by electroplating.

1. A textile comprising first and second conductive layers, at least oneporous layer positioned between the first and second conductive layers,the first and second conductive layers being arranged to generate anelectric field whereby a current passes between the conductive layers soas to induce liquid transport and so as to cause ions to be received atthe second conductive layer, measurement means arranged to measure theamount of charge transferred between the first and second conductivelayers during a liquid transport operation, the measurement means beingable to take account of any variation in current or voltage during theliquid transport operation, and control means arranged to control aregenerating operation to regenerate the second electrode bytransferring via it an amount of charge substantially equal to themeasured amount so as to cause ions to be removed from the secondconductive layer and thereby regenerate the conductive layer.
 2. Textileas claimed in claim 1, wherein the textile is arranged to be adjustableduring the induced liquid transport operation by varying the voltageapplied to the first and second conductive layers.
 3. Textile as claimedin claim 1, wherein the control means is arranged to control theregenerating operation by effecting a current reversal between the firstand second conductive layers.
 4. Textile as claimed in claims 1, whereinthe ions transported between the conductive layers are hydrogen ions,and the conductive layers contains a hydrogen storage material. 5.Textile as claimed in claim 1, wherein the porous layer has asymmetricalgeometry so as to cause more liquid transport when the electric field isapplied in the one direction than when it is applied in the oppositedirection.
 6. (canceled)
 7. Textile as claimed in claim 4, wherein thehydrogen storage material is palladium.
 8. Textile as claimed in claim4, wherein the hydrogen storage material is nanochrystalline nickel. 9.Textile as claimed in claim 2, wherein the control means is arranged tocontrol the regenerating operation by effecting a current reversalbetween the first and second conductive layers.
 10. Textile as claimedin claim 2, wherein the porous layer has asymmetrical geometry so as tocause more liquid transport when the electric field is applied in theone direction than when it is applied in the opposite direction. 11.Textile as claimed in claim 3, wherein the porous layer has asymmetricalgeometry so as to cause more liquid transport when the electric field isapplied in the one direction than when it is applied in the oppositedirection.
 12. Textile as claimed in claim 1, in an automotive seat, andfor water removal.
 13. Textile as claimed in claim 1, in a train seat,and for water removal.
 14. Textile as claimed in claim 1, in an airplane seat, and for water removal.
 15. Textile as claimed in claim 1, inclothing, and for water removal.
 16. Textile as claimed in claim 1, in amattress, and for water removal.
 17. Textile as claimed in claim 1, in ajacket, and for water removal.